Fuel injection pumps



June 24, 1958 J. N. MORRIS FUEL INJECTION PUMPS 2 Sheets-Sheet 1 Filed Feb. 24, 1956 INVENTOR ak/ mwa l ATTORNEYS.

mws m JOHN NEVILLE MORRIS.

FIG. I.

June 24, 1958 J. N. MORRIS FUEL INJECTION PUMPS 2 Sheets-Sheet 2 Filed Feb. 24, 1956 INVENTOR JOHN NEVILLE MORRIS.

BY ,'zmM/alj/ mdfi d ATTO EYS.

FUEL INJECTION PUMPS John Neville Morris, Birmingham, England, assignor of one-half to The S. U. Carburetter Co. Ltd., Birmingham, England, a British company, and one-half to Simmonds Aerocessories, Inc., Tarrytown, N. Y., a corporation of New York Application February 24, 1956, Serial No. 567,608

Claims priority, application Great Britain February 25, 1955 11 Claims. (Cl. 123-140) This invention relates to a fuel injection pump for internal combustion engines. More particularly, it is directed to a pump of thetypewherein means are provided for controllingthe delivery of one or more pump members as a function of the airiutake manifold pressure of the engine. 7 r x A pump of the above type will meter fuel correctly, i. e., in accordance with the air consumed per cycleby the engine, only so long as the manifold pressureaifords a true criterion of the amount of air inducedby the engine cylinders per cycle. That, however, does not hold United States Patent -O 2,840,066 Patented June 24, 1958 I 2 of fluid therethrough except when in the servo-valve closed position. i r Y I In accordance with the present invention a fuel-injection pump having its delivery controlled primarily as a function of the air induction manifold pressure of the engine is compensated for the deterioration in the mass of air induced percycle with-increasing speed by; the provision of means to be driven by the engine for modifying the pump delivery in a manner tending to decrease thedelivery withincreasingspeed for any given manifold pressure. More specifically the invention contemplates the provision of a centrifugal impellerto be drivenby the engine and having a fluid output coupled to modify the control which pressure responsive means have over the delivery of the pump. I A better understanding of the inventiOuwill he had frorna reading of the following detailed description with reference to the accompanying drawings in which:

- vFig. l is an elevational view partly in section showing a fuel injection pump embodying the present invention; Fig. 2 is'a fragmentary elevational view showing 'the servo-valve and the bifurcated lever for coupling the intrue at high engine speeds because of the obstructive effect of the inlet ports and valves, which results in a deterioration in the filling of the cylinders with increasing speed for a given intake manifold pressure. As a consequence, an undesirable 'richening of the fuel/air ratio occurs with increasing engine speed. This is particularly objectionable when the injection pump is intended for use with spark-ignition enginesof the type employed in automotive vehicles and in certain stationary installations where optimum fuel economy or operation is desired.

For convenience in explanation, the invention will be described with reference to onespecifictype of injection pump; however, as will appear from the description, the invention is applicable to all pumps of the general type referred to above.

The specific form of pump' with reference to which the invention is described in the following description is disclosed and claimed in my copending application Ser. No. 567,395 filed February 23, 1956. In the aforesaid application there is provided; an adjustable device which is made upof an adjustable element for controlling the delivery of the pump members and a displaceable-pressure responsive member for controlling theadjustable element. The displaceable'member is disposed in a housing so as to form with said housing a first and a second pressure chamber 011 respective sides of the displaceable member. Means are provided for supplying a substantially unrestricted flow of fluid under pressure tov the first pressure chamber. A servo-valve-controlled passage interconnecting the first and second pressure chambers is provided along with a servo-valve therefor. A restrict; ed passage is provided for venting the second pressure chamber. The opening in the valve-open position of the servo-valve is'chosen relative to the'size' of the restricted passage so as to permit; a rapid build-up of fluid pressure in the second pressure chamber when the servovalve is in its wide open position; This enables the pump to change its delivery rapidly in .a first direction. In

order to enable the pump to change rapidly in the reverse put signal thereto; 7 r r v Fig. 3 is a sectional view taken on line 33 in Fig. 2;

Fig. 4 is a fragmentary sectional'view showing a moditied construction of the servo-valve and baflle member forming a part of the present invention; and r Fig. 5 isa group of curves demonstrating the operating characteristics of the invention. 1

Referring now to the drawings, the fuel injection pump is provided with a cast housing 10 having acapsule pressure chamber 12 and an operating chamber 14. A drive shaft 16 passes through the chamber 14. and h as its upper end, which is not shown in thedrawing, operatively connected to' a distributing valve arrangement for sequentially connecting the pump cylinders,10ne of which is shown-at 18, to the fuel supply and to the injection nozzles for the engine. The other end of the drive shaft isarranged to be driven by the engine in a suitable manner. The cylinder 18 along with a suitable number of further cylinders, not shown, are positioned in the form of a circle in a cylinder block 20. Each of the cylinders is provided with a pumpmember in the form'ofa plunger 22 of which two are visible in the drawing. The plungers 22 bear against a wobble-plate 24 which is mounted upon a combined skew shaft and servo-piston unit 26. The unit 26 is slidably mounted 10. This surface may be generally spherical in nature.

position.

As the combined skew' shaft and servo piston'unit '26 moves longitudinally along the drive shaft 16the skew portionof the unit 26 will displace the .center ofdthe wobble-plate 24 therby increasing or decreasing its'tilt or. inclination. In a known manner rotation of the skew shaft will cause the wobble-plate to reciprocate the pumpmem'bers 22. As shown in the drawing, the stroke .of. the pump members will be a maximum when the unit,26 occupies its extreme upward position and will be a minimum when the unit 26 occupies its extreme lowermost.

Provision is made forconnecting a source of fluid under:

pressure to the housing 10 through the large port 36 e Pr e sid ieh assi tan s b ht l Piatins oil employed in the engine.- The fluid will fill-up the portion of the chamber 14 above the unit 26 (a first pressure chamber) and pass into a servo-valve-controlled passagess formed in the drive-shaft '16 by: way of the ports 40. It is noted that the ports 40 arelocated at a point 'on the' drive shaft 16 above theiipper limitof aa raoee a between the spring 62 and the thrust race 64 to be roinovenient of the servo-piston unit A further group of comparatively large ports 42 are located in the walls of fthe driveshaft 16 in communication withthe passage 38 in the lower. portion of thechamber 14 at a point well be lower limit of travel of the servo-piston unit A' servo-valve in the form of a cylindrical sleeve 'mleinbe r' fl is mounted for sliding movement longiupon the drive shaft 16. As shown in the the valve 44 is provided with a land ,area 46 yhich jcooperates with the ports 42 toprovide a variable obstruction "therefor dependent upon the: relative position of the servo-valve. As long as theports 42 are not eompietely obstructed or closed the pressure fluid will 'leavetheYpassage 38 through the ports 42 entering the enlarged internal portion 48 of the valve 44 and exiting lthrough the ports 50 formed in thewalls thereof. This t fluid' wi ll nowjcommenceto fill up, the portion of the chamber 14 located below the servo-piston26 (at second pressure chamber). i f

A second passage. 52 is formed within the 'drive shaft 161an'd communicates through a lateral passage54 with ftheexhrior of the housing 10. Theother end of the passage 52 communicates with. a plurality of port means 56 and .58 which arelocated in the shaft 16 within the lowerportion of chamber14. 1 The port means 56 is tated by the drive shaft 16. A battle member 92 is formed, as best seen in Fig. l, integral with the housing 10 and positioned around the intermediate portion of the servo-valve 44. The baflle member 92 has an opening 94 therein whichallows the servo-valve to move unobstructed therethrough with a slight clearance. The clearance also permits a somewhat restricted flow of the controlling. fluid between the first and second subsidiary chambers 96 and98 formed on respective sides of the baffle member. A passage 100 formed in the walls of the housing 10 interconnects the two subsidiary chambers 96 and 98. For apurpose to be described, the apron of the unit 26 has the lower portion of its outer snrfcae provided with a taper 102. n

In a modified form of the invention shown in Fig. 4 the integral battle m'emberof Fig. 1 has now been replaced by an annular ring 104 which is positioned within the bore 32 of the housing 10 so as to leave the portion Returning to Figs. 1, 2 and 3 the operation of the pump locatedwith respect to the servo-valve such that the lower. portion. 60- thereof completely obstructs the port means 56 for all positions of the servo-valve except that position wherein the land area 46 completely obstructs or closes oil the ports42', i. e. for all positions other than the servo-valve-closed position.- The reason for this will described below: I The other port means 58 is located at a point which is always unobstructed by the servo-valve arid-forms with thepassages 52 and 54 a permanent restricted passage for venting the aforementioned second pressure chamber in the-.lower'portionof chamber 14. The; ports 42 as well as theclearance 48 and ports in the'servo-valve should be of such size and proportion that the opening in the valve open position of the .servoyalve relative to the sizeflof, the restricted passage will permit a rapid build-up of pressure in the secondlpressure chamber belowtheservo-piston 26.

A. helical compression spring 62 surrounds the drive shaft '16 and is; disposedflbetween 'the web ..34 .of the servo piston 26. and the :upper face of the servo-valve 44.1 :A; thrustrace '64 isprovided between the spring 62 and;the tupper-face of the valve 44. The spring 62 urges the' yalve,44qdownwardly against the bifurcated ends 66 of an ar'ticulable link or see-saw lever 68 which straddles the drive shaft 16. A seen in Figs. 2 and 3 the ends 66 Oflthfl lever '68 are provided with tapered bearing surfaces 70 engaging V-n'otches 72 formed in the lower edge of the servo-valve 44. This prevents rotation of the servo-valve; and rat the sametime applies the controlling forc'e thereto The other end of the lever 68 'is acted upon! by a thrust. pin 74 which in turn is engaged by'a second thrustpin 76 fixed to onevface of a pressure responsive device 78 situated in the chamber12. The device may take the form of a sealed multi-capsule stack. i. The chamber 1 2 is provided with a port 80 for connection with the air induction manifold of the engine. The opposite face of the device 78 is positionedcentrally byanadjustableabutmentpin 82. i o g Thedevice as described so far corresponds with the disclosure inmy above-mentioned copending application.

will bediscussed first assuming that the impeller along with, bafile 92 and passage is omitted.

' So long as the operating conditions of the engine remain unchanged (i. e. while the induction manifold pressure applied to the capsule unit 'in the "chamber 12 remains constant), the mechanism described aboveis in a stable state. This arises-fromjthe circumstance that, under the conjoint influences of the control spring 62 and the load transmitted by the linkwork 68, 74 and 76 from the capsule unit 78, the servo-valve 44 assumes a position in which its landfarea 46 so regulates the efllux of fluid through theoutlet ports 42 that, in conjunctionwith the restricted provision for escape of fluid from the second pressurechamber, the differential fluid pressureacting on the servo-piston unit 26 exactly balances the load exerted by the control spring 62. Consequently, any given load exerted upon the servo-valve44 by the capsule unit 78 and its associated linkwork is necessarily exactly counterbalanced by the load exerted by the control spring 62, and, therefore, corresponds to aparticular length of that spring and hence'a definite position of the combined skew shaftand servo-piston unit 26. Thus, any given value of the induction manifold pressure results in a corresponding stroke being "performed by the fuel-pumping plungers 22. i

Let it be assumed that "the pump is in a stable fuelmetering condition with arelatively low pressure obtaining in the chamber 12; whichlof course, corresponds to the engine eitherfidling or being onlight load (that is to say whenthe throttle admitting air into the induction manifold is partially shut) i If new the throttle is abruptly opened, theinduction manifold pressure rises very rapidly, for example to atmospheric pressure or. to some pressure intermediate betweenthe low pressure previously existing and atmospher'ic pressure. The capsule unit 78 has a relatively low elasticity 'and,-therefore, thissudden insule' unit to'undergo a'substantial' contraction. This per-1 r'nits the servo-valve. 44 momentarily to slide under the influence'of the 'c'ontr'ol spring 62, it being borne in mind thatat theinstantpf opening 'thethrottle and consequently near was introduced by increasing the pump delivery for. the particular manifiold pressure prior to. including the correction of the centrifugal impeller.

sinner feature of the invention is that the weakening effect s described aboveis correlated with the output of revolution; that is to say, with the stroke of the pump plungers and, therefore, with the axial displacement oftheservo-piston unit 26. In this connection itwill berealized that the arrangement so far described depends for ineffectiveness upon free circulation of fluid .through[ the. passage. 100 interconnecting the two subsidiary chambers. .Qonsequently, if this passage is partially 1 obstructed {the fluid. pressure differentially which impeller] iii drivenrelationship to .the'internal combustionfengi'riefineans for. supplying fluidto said impeller, first fluid. couplingjmea'ns coupled to said impeller at a high pressure point therein, second fluid coupling means coupled to said impeller at a low pressure point therein, and meanscoupling said first and second fluid coupling means for exerting a differential force upon said servovalve in a manner tending to change its position, whereby a the delivery of said pump members iscontrolled as a actsupo'n thefcontrolmeans or servo-valve 44 will be nausea 1 Such. an effect is produced by the taper 102 on spmaisp r theservo-piston unit 26 which is arranged;progressively.' to overrun the mouth of the passage1100 ;'1heseleetion of the taper 102,0r alternatively the p qnlm erfuie mouth of the passage 100, can be so selected .asto} afford; any required correlation between the freedom ',of fluidc'irculation from the one subsidiary chamber ease otherQf'Ihus' the weakening effect can be..correlated iyvith'the'stroke of the plungers.

function of the speed of said engine.

3. A fuel injection pump for internal combustion engines having an adjustable wobble-plate for actuating a plurality of'pumping plungers of variable stroke, a com bined skew shaft and servo-piston unit keyed to andlongitudinally slidable on 'a drive shaft for altering the amplitude of the motion of the wobble-plate, and a housing for said combined skew shaft'and servo-piston unit forming with said unit a first and a second pressure chamber on respective sides of said 'unit, comprising in combination, means for supplying a substantially unrestricted flow of fluid under pressure to said first chamber, a servo- By rneans onthejeaturefjust'described, the force operativeupon the endfae 110.0: the servo-valve 44 can, fora given pump speed be, controlled in such a way thatthe weakening effect bears any. relationship (e. g. a lineanlrelationshimjI'to' the pump output per revolution and therefore, as would normally'be required, to produce a weakening eifectwhich would represent a constant percentagefofth'e pump output per stroke for any given speed. f

j In thee 'nbodimenttshown,in Fig. 4 the differential force; exerted upon [the{ servo-valve 44. is augmented by the flange 1 08 Asaresult of the difference in clearance between the valve 44 and. the baffle 104, and the flange 108 ,and the wall arms bore portion 106, substantially the whole :ofv the. fluid pressure :differentialoccurs across the flange ',10 8.,Sinee the flange increases the. surface area.uponwhich thefluid pressure differential is effective,

theforceideveloped isgreater than that developed in the" structure a of Fig.1 1'. f.

'Theinvention haybeen described with reference to a specific embodiment thereof, Nevertheless,'it is, intended to enc mpass: 1 he} numerous} changes and modifications which wiuiap ear' obvipusto those skilled, in the art to which is ,appertains and "which i come within the scope of th'e appended claims; j

ljWhatIclaim'isz v I, r r 1.- A fuel injection purnp .forfinternal combustion engines having an adjustable device; controlling the delivery of one'or more pump members, and a displacea'ble pressure responsive member for controlling the adjustable device disposed: in ahousing and forming with said housing a firstanda second pressure charnberon respective sidesof said member, comprising in combination, means for supplying a substantially unrestricted flow of fluid under pressure to said first chamber, a seryo-valve-controlled passageinterconnecting said two. chambersja servo-valve therefor,- a restricted passage for venting said second chamber, fluid .pressurizing means responsive to the speed of said pump for providing fluid underpressure with the pressure yarying as a function of said speed, and means coupling said pressurizing means'tosaid servo-valve for afpplyinga force thereto proportional to said pressure in a manner. tending to change the position of said servo-' valve,wherebyflthe delivery of said pump members is controlled a"s;a function of'the speed of said pump. ,,2. A fuel injection pump for internal combustion en-,

gines havingan adjustable elementcontrollingflthe delivery of, one'jormore pumpinernbers, a fluid operated servo-p ton for controlling the adjustable element, and laLve for: controllingjthe fluid pressure on oppo- J j i comprising in combinaing said second chamber, a fluid pressurizing means responsive to the speed of said pump for providing fluid under pressure. with the pressure varying as a function of said speed, and means coupling said fluid pressurizing means to said servo-valve for applying a force thereto proportional to said pressure in a manner tending to change the position of said servo-valve, whereby the stroke of said pump plungers is controlled as a function of the speed of said pump.

4. A fuel injection pump for internal combustion engines having an adjustable device controlling the delivery of one or more pump members, control means for positioning saidfadjusta'ble device, and pressure responsive means for coupling said control means to the air induction manifold of the engine for'regulating the control meansjih response to the air pressure in said manifold with increased delivery of said pump members corresponding to a rise in air pressure, and vice versa, said engine being of the type wherein the mass of air induced per cycle decreases with increasing speed above a given value for any given induction manifold pressure, comprising in combination a centrifugal impeller, drive means for coupling said impeller in driven relationship to the engine, means for supplying fluid to said impeller, and coupling means for coupling the output of said impeller for exerting a differential force upon said control means in a manner tending to change its position towards one calling for less delivery from the pump members with increase in said force, and vice versa, the relationship between said impeller output andthe regulating effect of said pressure responsive means being such as to cause the delivery of said pump members to be progressively decreased with increasing speed for any given induction manifold pressure at such a rate as to match said decrease in mass ofinduced air atspeeds above said given value to prevent thereby an undesirable richening of the fuel/ air ratio. H j

5. A fuel injection pump according to claim 4, wherein said adjustable device is provided with valve means directly coupled to said coupling means for modulating the fluid output of said impeller as a function of the delivery of said pump members, whereby the progressive decrease in delivery from said pump members is caused to vary as a function of the presssure in said air induction manifold in addition to varying as a functionof the speed of the engine.

-6. A fuel injection pump for internal combustion engines having a plurality of individual pump members for supplying fuel to the cylinders of said engine, an adjustable element for controlling the delivery of all of said pnmp rnembers ania' fluid operated servo-system includingafluid chamber'for regulating said adjustable element in direct response to the air induction manifold pressure of said engine, with increased delivery of said pump members corresponding to a rise in air pressure, and vice versa, said engine being of the type wherein the mass of air induced per cycle decreases with increasing speed above a given value for any given induction manifold pressure, comprising in combination an impeller disposed within said fluid chamber, drive means for coupling said impeller in driven relationship to the engine, and means for causing said impeller when driven by said engine to vary the output of said servo-system in a direction tending to decrease progressively said delivery of the pump members with increasing engine speed, and vice versa, whereby the delivery of fuel is caused to decrease with increasing speed so as to match said de crease in the induced air above said given value.

7. A fuel injection pump according to claim 6 wherein said impeller is constructed and arranged for developing a fluid pressure which varies as a direct function of the square of its speed of operation whereby the decrease in said delivery of fuel substantially follows a square law.

8. A fuel injection pump for internal combustion engines having an adjustable element for actuating a plurality of pumping plungers of variable stroke, a servopiston unit longitudinally slidable on a drive shaft for causing the adjustable element to alter the stroke of said plungers, a housing for said servo piston unit forming with said unit a first and a second pressure chamber on respective sides of said unit, means for supplying a substantially unrestricted flow of fluid under pressure to said first chamber, a passage formed within said drive shaft and extending beyond the limits of movement of said servo-piston unit on both sides thereof, one or more ports formed in the wall of said drive shaft on each side of said servo-piston unit for establishing communication between said passage and said first and second chambers, respectively, a servo-valve slida'bly mounted on said drive shaft within said second chamber for operative valving cooperation with the drive shaft ports therein, and means for coupling said drive shaft in driven relation to said engine; comprising in combination a baffle member surrounding an intermediate portion of said servo-valve with a slight clearance therebetween and dividing said second chamber into first and second subsidiary chambers with movement of said servo-valve into said first subsidiary chamber causing a decrease in the stroke of said plungers, a centrifugal impeller mounted on said drive shaft for driven rotation therewith within said first subsidiary chamber, and a passage in said housing establishing communication between both of said subsidiary chambers such that fluid tends to flow from the first to the second subsidiary chamber in response to a pressure differential being developed across said impeller, thereby to urge said servo-valve into said first subsidiary chamber with a force varying as a function of the speed of said shaft, whereby the stroke of said plungers is as a function of increasing engine speed.

9. A fuel injection pump according to claim 8, Wherein said servo-piston unit is provided with a portion making sliding contact with the walls of said housing within said second pressure chamber, said portion being constructed to variably obstruct the mouth of said passage which establishes communication between said subsidiary chambers as a function of the position of said servo-piston unit, to modify thereby. the amount by which the stroke of said plungers is decreased.

10. A fuel injection pump according to claim 8, where in said housing has a straight bore portion surrounding said servo-valve within said second subsidiary chamber with the walls thereof joined to said baflle member perpendicular thereto, and said servo-valve is provided with an annular radial flange fitting with a slight clearance within said bore portion, said last mentioned clearance being less than the clearance existing between the servovalve and the baflle member so as to increase the force acting upon said servo-valve in response to a given rise in pressure across said impeller, thereby to increase the sensitivity of the pump.

1-1. A fuel injection pump for internal combustion endecreased gines having its delivery controlled primarily as a function of the air induction manifold pressure of the engine and compensated for the deterioration in the mass of air induced per cycle by the engine with increasing speed above a given value for any given induction manifold pressure, comprising in combination a fuel pumping device, a pressure responsive means for controlling the delivery per cycle of said pumping device as a function of said manifold pressure with increased delivery corresponding to rise in manifold pressure, and vice versa, a centrifugal impeller, means for coupling said impeller in driven relationship to said engine, means for supplying said impeller with a fluid, and means coupling an output of said impeller to said pressure responsive means for modifying its control of the delivery of said pumping device in a manner tending to decrease the delivery with increasing speed, the relationship between impeller output and the control exercised by said pressure responsive means being such as to cause the delivery of fuel to deteriorate with increasing speed at such a rate as to match said deterioration in the induced air at speeds above said given value to prevent thereby an undesirable richening of the fuel/ air ratio.

References Cited in the file of this patent UNITED STATES PATENTS 2,438,663 Greenland Mar. 30, 1948 2,673,556 Reggio Mar. 30, 1954 FOREIGN PATENTS 696,791 Great Britain Sept. 9, 1953 

